The present invention relates generally to an automotive wiper device. More specifically, the invention relates to a wiper device with adjustable force of depression against the windshield. Further specifically, the invention relates to an adjustable-force wiper device which can be adjusted linearly.
As is well known, automotive wiper devices include wiper blades mounted on the ends of wiper arms. Springs seated between the wiper blades and the wiper arms exerted a spring force depressing the wiper blades against window surfaces. So that the wiper blades can effectively wipe away rain water, washer liquid and so forth, the force of depression of the wiper blades against the window surface must be adequate. The required depression force varies with vehicle driving conditions. For example, when the vehicle is moving at high speed or into a strong wind, a greater depression force is required so as to prevent the wiper blade from being lifted off the window surface. On the other hand, when the vehicle is moving at a relatively low speed, i.e. when the wiper blade is not subjected to a powerful air flow, less depression force is required. If the depression force is adjusted to be sufficient to prevent the wiper blade from being lifted off during high-speed travel, the depression force may be excessively high, which would accelerate wear on the wiper blade and so shorten its lifetime and may increase the chance of scratching the window surface. On the other hand, when the wiper blade depressing force is adjusted for normal, relatively low-speed driving, the wiper blades will tend to be displaced and so may not effectively wipe away rain water, washer liquid and so forth from the window surface.
Therefore, it would be advantageous to allow adjustment of the depression force of automotive wiper devices so that the depression force of the wiper blades can be adjusted according to the vehicle driving conditions. It would be preferable to allow adjustment of the depression force of the wiper blades by remote control from the vehicle cabin. Furthermore, in order to allow remote control of the depression force of the wiper blades, it would be best for the depression force to vary linearly.